How to use AutoMapper for Sub-Objects in C#?

Question

I do have two classes:

public class Data
{
    public string? Property1 { get; set; }
    public string? Property2 { get; set; }
    public int Quantity { get; set; } = 1;
}

public class DataQuantity
{
    public Data Data { get; set; } = null!;
    public int Quantity { get; set; } = 1;
}

I want to use AutoMapper to map a "DataQuantity"-object to a "Data"-opject, where the Quantity from DataQuantity overwrites the Quantity from Data. If possible, I don't want to name all properties.

I've tried simple maps like:

CreateMap<DataQuantity, Data>()
    .ForMember(dest => dest.Quantity, opt => opt.MapFrom(src => src.Quantity));

In my service I call it like this:

var data = _mapper.Map<Data>(dataqty);

In "dataqty" all props are filled. After the mapping "data" props are all null or default.

dotnetfiddle: https://dotnetfiddle.net/5DZopv

Any help is welcome.

Answer 1

You can use IncludeMembers to perform "customized" flattening:

cfg.CreateMap<Data, Data>();
cfg.CreateMap<DataQuantity, Data>().IncludeMembers(s => s.Data);

Demo @dotnetfiddle.net